JP2009160833A - Ink jet printer, nozzle cleaning method and control program for ink jet printer - Google Patents

Abstract

Ink consumption by cleaning is suppressed.
The print head is driven so that the print recording liquid is ejected from the nozzle, and the print head is driven from above the inspection area provided at the position where the print medium is not arranged, and the print recording is performed from the nozzle of the print head. Detection means for outputting discharge information indicating whether or not the liquid has been discharged, control means for executing the detection means for each nozzle in a state where the print head is disposed above the inspection area, and discharge from the discharge information for each color A non-ejection number calculating means for calculating the number of clogged nozzles, a discharge number calculating means for calculating the number of discharges for each color to be analyzed for printing image data to be printed, and the total number of clogged nozzles. An inkjet printer comprising: a cleaning determination unit that determines whether or not to clean the print head based on the number of clogged nozzles and the number of ejections when the number is 1 or more.
[Selection] Figure 5

Description

  The present invention relates to an inkjet printer equipped with a nozzle clogging detection function, a nozzle cleaning method for an inkjet printer, and a control program.

  Conventionally, as an ink jet printer, an ink droplet ejected from a nozzle of a print head is charged, and the charged ink droplet is ejected to a portion (inspection area) that receives the ink droplet facing the nozzle, which is caused by the ejection of the ink droplet. A device that inspects whether or not an ink droplet is actually ejected from a nozzle by detecting an induced voltage is known (see, for example, Patent Document 1). Further, a light beam is formed in a direction intersecting the ejection direction in which the ink droplet is ejected from the nozzle of the print head, and the ink droplet is ejected from the nozzle by detecting whether the ink droplet ejected from the nozzle blocks the light beam. There is also known an apparatus that inspects whether or not the liquid is actually discharged (see, for example, Patent Document 2).

  However, Patent Documents 1 and 2 do not examine in detail the timing of performing an inspection (referred to as nozzle inspection) as to whether or not an ink droplet has actually been ejected from a nozzle.

  In order to solve this problem, for example, Patent Document 3 describes a method for determining the timing of nozzle inspection based on the print quality level included in a print job.

JP 59-120464 A JP 2005-35309 A JP 2007-118560 A

  However, according to the conventional method, even when nozzles of colors that are rarely used are clogged depending on the data to be printed, all of the nozzles are cleaned, so ink of unused colors is consumed, and before printing, However, there is a problem that the user waits until the cleaning is completed.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
An inkjet printer that performs printing on a print medium using a print head having a plurality of nozzles that discharge a plurality of print recording liquids of colors, wherein the print head is configured to discharge the print recording liquid from the nozzles And a discharge means for driving the print head from above the inspection area provided at a position where the print medium is not disposed and whether the print recording liquid is discharged from the nozzle of the print head. Detection means for outputting, control means for executing the detection means for each nozzle in a state where the print head is arranged above the inspection area, and the number of clogged nozzles that have not been discharged for each color from the discharge information A non-ejection number calculating means for calculating the number of ejections, and an ejection number calculating means for calculating the number of ejections for each of the colors to be ejected for analyzing and printing image data to be printed. Cleaning determination means for determining whether or not the print head is to be cleaned based on the number of clogged nozzles and the number of ejections when the total number of clogged nozzles is 1 or more. Inkjet printer.

  According to this configuration, if there is a clogged nozzle and the detected color is hardly used in the print data, printing can be performed without cleaning, thus reducing ink consumption while maintaining print quality. Can do.

[Application Example 2]
In the inkjet printer described above, the inkjet printer includes a determination table that defines the number of clogged nozzles and the number of ejections for each color for determining that the cleaning is performed, and the cleaning determination unit includes: An inkjet printer that determines whether or not to clean the print head based on the determination table.

  According to this configuration, if there is a clogged nozzle and the detected color is hardly used in the print data, printing can be performed without cleaning, thus reducing ink consumption while maintaining print quality. Can do.

[Application Example 3]
In the ink jet printer described above, the print head is cleaned after printing when the total number of clogged nozzles is 1 or more and the cleaning determination unit determines not to perform cleaning in a print waiting state. Inkjet printer.

  According to this configuration, when the color detected when there is a clogged nozzle is hardly used in the print data, cleaning is performed after printing, so the waiting time until the completion of printing is longer than when cleaning is performed before printing. Further, the print quality can be ensured in the next print job by performing cleaning in the idle time after printing.

[Application Example 4]
A nozzle cleaning method for an ink jet printer that performs printing on a print medium using a print head having a plurality of nozzles that discharge a plurality of print recording liquids of a plurality of colors, wherein the print recording liquid is discharged from the nozzles A driving step for driving the print head, and whether the print recording liquid is discharged from the nozzle of the print head by driving the print head from above an inspection area provided at a position where the print medium is not disposed. A detection step for outputting the discharge information, a control step for executing the detection step for each nozzle in a state where the print head is disposed above the inspection region, and no discharge was performed for each color from the discharge information. A non-ejection number calculating step for calculating the number of clogged nozzles, and calculating the number of ejections for each of the colors ejected to analyze and print the image data to be printed. And a cleaning determination step for determining whether to perform cleaning of the print head based on the number of clogged nozzles and the number of discharges when the total number of clogged nozzles is 1 or more. A nozzle cleaning method for an ink jet printer, comprising:

  According to this configuration, if there is a clogged nozzle and the detected color is hardly used in the print data, printing can be performed without cleaning, thus reducing ink consumption while maintaining print quality. Can do.

[Application Example 5]
A nozzle cleaning control program for an ink jet printer that performs printing on a print medium using a print head having a plurality of nozzles that discharge a plurality of print recording liquids of colors, wherein the print recording liquid is discharged from the nozzles. A driving step for driving the print head, and whether the print recording liquid is ejected from the nozzle of the print head by driving the print head from above an inspection area provided at a position where the print medium is not disposed. A detection step for outputting the discharge information, a control step for executing the detection step for each nozzle in a state where the print head is disposed above the inspection area, and no discharge for each color from the discharge information. A non-ejection number calculating step for calculating the number of clogged nozzles, and discharging for analyzing and printing the image data to be printed. Whether or not the print head is cleaned based on the number of clogged nozzles and the number of discharges when the sum of the number of times of discharge and the number of clogged nozzles is 1 or more. A nozzle cleaning control program for an ink jet printer, comprising: a cleaning determination step for determining whether or not.

  According to this configuration, if there is a clogged nozzle and the detected color is hardly used in the print data, printing can be performed without cleaning, thus reducing ink consumption while maintaining print quality. Can do.

  Hereinafter, embodiments of an inkjet printer will be described with reference to the drawings.

(First embodiment)
<Inkjet printer configuration>
First, the configuration of the inkjet printer according to the first embodiment will be described with reference to FIG. FIG. 1 is a perspective view showing the configuration of the ink jet printer according to the first embodiment.

  As shown in FIG. 1, the inkjet printer 20 includes a printer mechanism 21 including a print head 24 and a carriage 22, a paper feed mechanism 31 including a paper feed roller 35 driven by a drive motor 33, and a platen 44. A cap device 40 formed near the right end, a nozzle inspection device 50 formed near the left end on the platen 44 and inspecting whether ink droplets are normally ejected from the print head 24, and the entire inkjet printer 20 are controlled. And a controller 70.

  The printer mechanism 21 includes a carriage 22 that reciprocates left and right along a guide 28 by a carriage belt 32 and a carriage motor 34, and mounted on the carriage 22, yellow (Y), magenta (M), cyan (C), and black (K) ink cartridges 26 that individually store inks of each color, a print head 24 that applies pressure to each ink supplied from each ink cartridge 26, and ink droplets that have been pressurized by the print head 24 are recorded on recording paper. A nozzle 23 serving as an emission hole for discharging to S and a platen 44 serving as a support member for supporting the recording paper S being printed are provided. In this embodiment, pigment ink is used as the ink. A linear encoder 25 that detects the position of the carriage 22 is disposed in the vicinity of the carriage 22, and the position of the carriage 22 can be managed using the linear encoder 25. Although not shown, the ink cartridge 26 is used for printing cyan (C), magenta (M), yellow (Y), black (K), etc. containing dye or pigment as a colorant in water as a solvent. The container is configured as a container for storing ink as a recording liquid, and is detachably attached to the carriage 22.

<Configuration of print head>
Next, the configuration of the print head will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the print head.

  As shown in FIG. 2, the print head 24 is provided with a nozzle array 43 in which a plurality of nozzles 23 for ejecting ink of each color of cyan (C), magenta (M), yellow (Y), and black (K) are arranged. It has been. Here, all nozzles are collectively referred to as nozzles 23, all nozzle rows are collectively referred to as nozzle rows 43, cyan nozzles and nozzle rows are nozzles 23C and 43C, magenta nozzles and nozzle rows are nozzles 23M. The nozzle row 43M, the yellow nozzle and the nozzle row are referred to as a nozzle 23Y and a nozzle row 43Y, and the black nozzle and the nozzle row are referred to as a nozzle 23K and a nozzle row 43K. Hereinafter, description will be given using the nozzle 23K. In the print head 24, 180 nozzles 23 </ b> K are arranged along the conveyance direction of the recording paper S to form a nozzle row 43 </ b> K. The nozzle 23K is provided with a piezoelectric element 48 as a drive element for ejecting ink droplets. By applying a voltage to the piezoelectric element 48, the piezoelectric element 48 is deformed to pressurize and eject ink from the nozzle 23K. To do.

  The print head 24 includes a plurality of mask circuits 47 provided corresponding to the plurality of piezoelectric elements 48 that drive the respective nozzles 23K. The original signal ODRV and the print signal PRTn generated by the controller 70 are input to the mask circuit 47. Note that n at the end of the print signal PRTn is a number for specifying the nozzles included in the nozzle row. In this embodiment, since the nozzle row is composed of 180 nozzles, n is any number from 1 to 180. It becomes a numerical value. This original signal ODRV has a first pulse P1, a second pulse P2, a third pulse P3, as shown in the lower part of FIG. 2, within a period of one pixel (within the time during which the carriage 22 crosses the interval of one pixel). It consists of three drive waveforms. In the present embodiment, the original signal ODRV having these three drive waveforms as a repeating unit is referred to as one segment. When the original signal ODRV and the print signal PRTn are input, the mask circuit 47 transmits a necessary pulse among the first pulse P1, the second pulse P2, and the third pulse P3 based on these signals to the drive signal DRVn (n Is the same as n of the print signal PRTn) and is output toward the piezoelectric element 48 of the nozzle 23K.

  Specifically, when only the first pulse P1 is output from the mask circuit 47 to the piezoelectric element 48, one shot of ink droplet is ejected from the nozzle 23K, and a small size dot (small dot) is formed on the recording paper S. It is formed. When the first pulse P1 and the second pulse P2 are output to the piezoelectric element 48, two shots of ink droplets are ejected from the nozzle 23K, and medium-sized dots (medium dots) are formed on the recording paper S. The When the first pulse P1, the second pulse P2, and the third pulse P3 are output to the piezoelectric element 48, three shots of ink droplets are ejected from the nozzle 23K, and a large size dot (large size) is formed on the recording paper S. Dot) is formed. Thus, in the inkjet printer 20, it is possible to form dots of three types of sizes by adjusting the amount of ink ejected in one pixel section. The other color nozzles 23C, 23M, and 23Y and the nozzle rows 43C, 43M, and 43Y are the same as the nozzle 23K and the nozzle row 43K. Here, the print head 24 employs a method in which the piezoelectric element 48 is deformed to pressurize the ink, but the ink is generated by bubbles generated by heating the ink by applying a voltage to a heating resistor (for example, a heater). You may employ | adopt the system which pressurizes.

<Configuration of paper feed mechanism>
Next, the configuration of the paper feed mechanism will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of the paper feed mechanism.

  As shown in FIG. 3, the recording paper insertion slot 18 into which the recording paper S placed on the paper feeding tray 14 is inserted, and the paper feeding that supplies the recording paper S placed on the paper feeding tray 14 to the print head 24. A roller 36, a paper feed roller 35 that conveys the recording paper S and roll paper to the print head 24, and a paper discharge roller 37 that discharges the printed recording paper S are provided. The paper feed roller 36, paper feed roller 35, and paper discharge roller 37 are driven by a drive motor 33 (see FIG. 1) via a gear mechanism (not shown). A plurality of recording sheets S are prevented from being fed at a time by the rotational driving force of the sheet feeding roller 36 and the frictional resistance of a separation pad (not shown). In FIG. 1, the conveyance direction of the recording sheet S is a direction from the back side toward the front side, and the movement direction of the carriage 22 that moves together with the print head 24 is a direction (main scanning direction) orthogonal to the conveyance direction of the recording sheet S. .

<Configuration of nozzle inspection device>
Next, the configuration of the nozzle inspection apparatus will be described with reference to FIG. FIG. 4 is a block diagram showing the configuration of the nozzle inspection apparatus.

  As shown in FIG. 4, the nozzle inspection device 50 includes an inspection box 51 in which ink droplets flying from the nozzles 23 of the print head 24 can land, and a predetermined distance from the print head 24 provided in the inspection box 51. Provided, a voltage application circuit 53 for applying a voltage between the inspection area 52 and the print head 24, and a voltage detection circuit 54 for detecting the voltage of the inspection area 52. The inspection box 51 is a housing that is provided at a position off the left side from the printable area of the platen 44 and is a substantially rectangular parallelepiped with an upper portion opened.

  The inspection area 52 is provided in the inspection box 51, and an upper ink absorber 55 on which ink droplets directly land, and a lower ink that absorbs ink droplets that have been transmitted downward after landing on the upper ink absorber 55. The absorber 56 and a mesh-like electrode member 57 disposed between the upper ink absorber 55 and the lower ink absorber 56 are configured. The upper ink absorber 55 is made of a conductive sponge so as to have the same potential as the electrode member 57, and the surface thereof is an inspection region 52. This sponge is highly permeable so that the landed ink droplets can move down quickly, and here, an ester urethane sponge (trade name: Everlite SK-E, manufactured by Bridgestone Corporation) is used. Yes. The lower ink absorber 56 has higher ink retention than the upper ink absorber 55 and is made of a nonwoven fabric such as felt. Here, the nonwoven fabric (trade names: Kinocloth, Oji Kinocross Co., Ltd.) Made).

  The electrode member 57 is formed as a grid-like mesh made of a metal made of stainless steel (for example, SUS). For this reason, the ink once absorbed by the upper ink absorber 55 is absorbed and held by the lower ink absorber 56 through the gap between the grid-like electrode members 57. The voltage application circuit 53 is electrically connected via a DC power source (for example, 400 V), a resistance element (for example, 1 MΩ), and a switch SW so that the electrode member 57 is a positive electrode and the print head 24 is a negative electrode. . Here, since the electrode member 57 is in contact with the conductive upper ink absorber 55, the surface of the upper ink absorber 55, that is, the inspection region 52 is also at the same potential as the electrode member 57.

  The voltage detection circuit 54 is connected so as to detect the voltage of the electrode member 57 equated with the voltage of the inspection region 52, integrates and outputs the voltage signal of the electrode member 57, and the integration circuit 54a. An inverting amplification circuit 54b that inverts and amplifies the output signal and outputs the signal, and an A / D conversion circuit 54c that A / D converts the signal output from the inverting amplification circuit 54b and outputs the signal to the controller. The integration circuit 54a outputs a large voltage change by integrating the voltage change due to the flight / landing of a plurality of ink droplets since the voltage change due to the flight / landing of one ink droplet is small. The inverting amplifier circuit 54b inverts the sign of the voltage change and amplifies and outputs the signal output from the integrating circuit 54a at a predetermined amplification factor determined by the circuit configuration. The A / D conversion circuit 54 c converts the analog signal output from the inverting amplification circuit 54 b into a digital signal and outputs the digital signal to the controller 70.

  As shown in FIG. 1, the cap device 40 is used when sealing the nozzles 23 in order to prevent the nozzles 23 from being dried during a printing pause or the like. The cap device 40 is operated so as to cover the nozzle formation surface of the print head 24 when the print head 24 moves together with the carriage 22 to the right end (referred to as a home position). The cap device 40 is connected to a suction pump (not shown). For example, when nozzle clogging is detected by the nozzle inspection device 50, the negative pressure of the suction pump is applied to the nozzle forming surface of the print head 24 sealed by the cap device 40 as necessary. The ink clogged from 23 is sucked and discharged. Note that the waste ink discharged and collected is stored in a waste liquid tank (not shown).

  As shown in FIG. 1, the controller 70 is configured as a microprocessor centered on the CPU 72, and includes a ROM 73 that stores various processing programs, a RAM 74 that temporarily stores data and stores data, A flash memory 75 that can write and erase data, an interface (I / F) 79 that exchanges information with an external device, and an input / output port (not shown) are provided. The ROM 73 stores processing programs for a main routine and a nozzle inspection routine, which are control means, and a print processing routine, which will be described later. The RAM 74 is provided with a print buffer area, and print data sent from the user PC 10 via the I / F 79 is stored in this print buffer area. In addition to the voltage signal output from the voltage detection circuit 54 of the nozzle inspection device 50 and the position signal of the carriage 22 from the linear encoder 25 being input to the controller 70 via an input port (not shown), the user PC 10 A print job or the like output from is input via the I / F 79. Further, from the controller 70, a control signal to the print head 24 (including the mask circuit 47 and the piezoelectric element 48), a control signal to the drive motor 33, a drive signal to the carriage motor 34, and an operation control signal to the cap device 40. Are output via an output port (not shown), and print status information to the user PC is output via the I / F 79.

<Operation of inkjet printer>
Next, the operation of the ink jet printer will be described with reference to FIG. FIG. 5 is a flowchart showing the operation of the ink jet printer. This routine is executed by the CPU 72 at predetermined timings (for example, every several milliseconds) after the power of the inkjet printer 20 is turned on.

  When this routine is started, the CPU 72 first determines in step S100 whether or not there is a print job waiting for printing. Since the print job received from the user PC 10 is stored in the print buffer area formed in the RAM 74 and becomes a print job waiting to be printed, when the print job is received, it can be printed immediately as well as during printing. Even so, the print job is waiting for printing. If there is no print job waiting for printing in step S100, the main routine is terminated. If there is a print job, the process proceeds to step S102.

  In step S102, the image data stored in the print buffer area is read.

  Next, in step S104, it is determined whether or not it is the inspection timing for performing the nozzle inspection. If it is the inspection timing, the process proceeds to step S106, and if it is not the inspection timing, the process proceeds to step S110. The inspection timing is determined from the time elapsed since the previous nozzle inspection was performed, the number of print head discharges, the number of printed sheets, and the like.

  Next, in step S106, a nozzle inspection routine is executed.

  Here, the operation of the nozzle inspection routine will be described with reference to FIG. FIG. 8 is a flowchart showing the operation of the nozzle inspection routine.

  When the nozzle inspection routine is started, first, in step S300, the CPU 72 turns on the switch SW of the voltage application circuit 53 to generate a predetermined potential difference between the inspection region 52 and the print head 24, and the current inspection. The position, that is, the position of the inspection region 52 that ejects ink from the nozzle 23 is acquired. Here, since the solid matter contained in the ink may be deposited on the surface of the inspection area 52 due to the ejection of the ink, the inspection position is set to change every time the nozzle inspection routine is executed.

  FIG. 9 is an explanatory diagram of the inspection position in the nozzle inspection process. In FIG. 9, a plurality of inspection positions p1, p2, p3, and p4 are set. In one nozzle inspection routine, each nozzle row 43 has a variation in the detected value of the dielectric voltage due to the difference in the inspection position. The ink is set to be ejected to the same inspection position. For example, when the current nozzle inspection is performed at the inspection position p1, the nozzle row 43Y is first positioned so as to face the inspection position p1, and ink droplets are ejected from the nozzles 23Y included in the nozzle row 43Y. Next, the nozzle row 43M is positioned so as to face the inspection position p1, and ink droplets are ejected from the nozzles 23M included in the nozzle row 43M. Thereafter, the nozzle rows 43C and 43K are similarly tested at the inspection position p1. Ink droplets are ejected from the nozzles 23C and 23K. Further, the ink is ejected to a position different from the current inspection position at the next inspection position so that the solid content of the ink is not excessively accumulated only at a certain inspection position. For example, when the current nozzle inspection is performed at the inspection position p1, the next nozzle inspection is performed at the inspection position p2.

  Returning to the description of the nozzle inspection routine of FIG. 8, in step S310, after acquiring the current inspection position in step S300, the CPU 72 drives the carriage motor 34 and the nozzles to be inspected in the nozzle row 43 of the print head 24. The carriage 22 is moved so that the row 43 faces the current inspection position.

  Next, in step S320, an ink droplet charged from the nozzle 23 is ejected through the mask circuit 47 and the piezoelectric element 48 (see FIG. 2) of one nozzle 23 in the nozzle row 43 to be inspected.

  Here, a change in voltage in the electrode member 57 when the charged ink droplets fly from the nozzles 23 of the print head 24 and reach the inspection region 52 including the upper ink absorber 55 will be described with reference to FIG. FIG. 10 is an explanatory diagram of the principle that an induced voltage is generated by electrostatic induction. As shown in FIG. 10A, the ink droplet before flying from the nozzle 23 by the print head 24 is negatively charged by the voltage application circuit 53. In addition, since the print head 24 and the inspection area 52 are arranged at a distance and a predetermined potential difference is generated between them, a predetermined electric field strength (= potential difference / distance) is generated between them. Yes. For this reason, as shown in FIG. 10B, as the negatively charged ink droplets fly from the nozzle 23 and approach the upper ink absorber 55, the surface of the upper ink absorber 55 is positively applied by electrostatic induction. The charge increases. As a result, the voltage between the print head 24 and the electrode member 57 becomes higher than the initial voltage value due to the induced voltage generated by electrostatic induction.

  Thereafter, as shown in FIG. 10C, when the negatively charged ink droplet reaches the upper ink absorber 55, the positive charge of the upper ink absorber 55 is neutralized by the negative charge of the ink droplet. As a result, the voltage between the print head 24 and the electrode member 57 is lower than the initial voltage value. Thereafter, the voltage between the print head 24 and the electrode member 57 returns to the applied voltage value. The amplitude of the output signal at this time depends not only on the distance from the print head 24 to the upper ink absorber 55 (inspection region 52), but also on the presence or size of flying ink droplets. For this reason, when the nozzle 23 is clogged and the ink droplet does not fly or the ink droplet is smaller than a predetermined size, the amplitude of the output signal becomes smaller than the normal time. The presence or absence of clogging can be determined.

  In the present embodiment, even if the ink droplet has a predetermined size, the amplitude of the output signal from the ink droplet for one shot is extremely small. Therefore, one segment of the first to third pulses P1, P2, representing the drive waveform. By performing the operation of outputting all of P3 eight times, ink droplets for 24 shots are ejected. As a result, the output signal becomes an integrated value of ink droplets for 24 shots, and thus a sufficiently large output waveform can be obtained from the voltage detection circuit 54. Note that the direction of the amplitude of the signal output from the voltage detection circuit 54 is reversed because it passes through the inverting amplification circuit 54b.

  Returning to the description of the nozzle inspection routine of FIG. 8, in step S330, the ink charged from the nozzle 23 via the mask circuit 47 or the piezoelectric element 48 of one nozzle 23 in the nozzle row 43 to be inspected in this way. After ejecting the droplet, the CPU 72 determines whether the amplitude of the signal output from the voltage detection circuit 54, that is, the output level is equal to or higher than the threshold value Vthr. If the threshold value is equal to or higher than the threshold value Vthr, the CPU 72 proceeds to step S350. In this case, the process proceeds to step S340. As shown in FIG. 11, the threshold value Vthr exceeds the output level when ink for 24 shots is normally ejected, and exceeds noise due to noise or the like when ink for 24 shots is not ejected normally. It is a value determined empirically so that nothing happens.

  Next, in step S340, it is considered that an abnormality such as clogging has occurred in the current nozzle 23, and discharge information (for example, information indicating which nozzle row in which nozzle row) that identifies the nozzle 23 is stored in the RAM 74 in a predetermined manner. Store in the area.

  Next, in step S350, the CPU 72 determines whether all the nozzles 23 included in the nozzle row 43 currently being inspected have been processed, and inspected all the nozzles 23 included in the nozzle row 43 currently being inspected. When the inspection is performed, the process proceeds to step S370, and when all the nozzles 23 included in the nozzle row 43 currently inspected are not inspected, the process proceeds to step S360.

  Next, in step S360, when there is an uninspected nozzle 23 in the nozzle row currently being inspected, the nozzle 23 to be inspected is updated to an uninspected nozzle, and then the processes in and after step S320 are performed again.

  On the other hand, in step S370, it is determined whether or not processing has been performed for all nozzle arrays 43 included in the print head 24. If all nozzle arrays 43 have been inspected, the process proceeds to step S390, and all nozzle arrays 43 are processed. If the inspection is not performed for 43, the process proceeds to step S380.

  Next, in step S380, the nozzle row 43 to be inspected is updated to an uninspected nozzle row 43, and then the processes in and after step S310 are performed again.

  On the other hand, in step S390, the switch SW of the voltage application circuit 53 is turned off, and this nozzle inspection routine ends.

  By executing this routine, if there is a nozzle 23 in which an abnormality has occurred among all the nozzles 23 arranged in the print head 24, information for specifying the nozzle 23 is stored in the predetermined area of the RAM 74. If there is no nozzle 23 in which an abnormality has occurred, nothing is stored.

  Returning to the description of the main routine in FIG. 5, after executing the above-described nozzle inspection routine (step S106), the CPU 72, in step S108, out of all the nozzles 23 arranged in the print head 24, is an abnormal nozzle. 23 is determined based on the stored contents of the predetermined area of the RAM 74. If there is a nozzle 23 in which an abnormality has occurred, the process proceeds to step S112. If there is no nozzle 23 in which an abnormality has occurred, The process proceeds to step S110.

  Next, in step S112, which is a non-discharge number calculating means, the number of clogged nozzles for each color is calculated from the discharge information stored in a predetermined area of the RAM 74.

  Next, in step S114, which is a discharge number calculation means, the read image data is discharged and the number of discharges for each color discharged for printing is calculated.

  Next, in step S116, which is a cleaning determination unit, it is determined whether or not the print head is to be cleaned based on the number of clogged nozzles for each color, the number of ejections for each color, and the determination table shown in FIG. If so, the process proceeds to step S118. If cleaning is not performed, the process proceeds to step S122.

  FIG. 6 is a table showing the configuration of the determination table. The determination table includes yellow (Y), magenta (M), cyan (C), and black with the number of clogged nozzles for each color used for determination by the cleaning determination unit and the threshold for the number of ejections for each color mounted on the carriage 22. It is defined for each color ink of (K). For example, when the number of nozzles clogged with black (K) is 50 or less and the number of discharges is 30 or less, it is determined that cleaning is not performed, and the number of clogged nozzles with cyan (C) is 10 or less and the number of discharges is 5 or less. In this case, it is determined that cleaning is not performed, and when the number of clogged nozzles of magenta (M) is 20 or less and the number of ejections is 10 or less, it is determined that cleaning is not performed, and the number of clogged nozzles of yellow (Y) is 30. If the number of discharges is 20 or less, it is determined that cleaning is not performed.

  Next, in step S118, the print head 24 is cleaned. Specifically, the carriage motor 34 is driven to move the carriage 22 until the print head 24 comes to the home position facing the cap device 40, and the cap device 40 is operated so that the cap device 40 forms the nozzles of the print head 24. After covering the surface, the negative pressure of a suction pump (not shown) is applied to the nozzle forming surface to suck and discharge the clogged ink from the nozzle 23.

  Next, in step S120, Flag = OFF is set to indicate that cleaning is not performed after printing, and the flow proceeds to step S106 to confirm the cleaning effect, and the nozzle inspection routine is executed again.

  On the other hand, in step S122, Flag = ON is set to indicate that cleaning is to be performed after printing, and the process proceeds to the printing processing routine in step S110.

  Next, in step S110, the CPU 72 executes a print processing routine.

  FIG. 7 is a flowchart showing the operation of this print processing routine.

  When the print processing routine is started, first, in step S200, the CPU 72 executes a paper feed process. The paper feed process is a process of conveying the recording paper S placed on the paper feed tray 14 to the paper feed roller 35 by driving the drive motor 33 to rotate the paper feed roller 36 (see FIG. 3).

  Next, in step S202, the CPU 72 drives the carriage motor 34 to eject the ink from the print head 24 while moving the carriage 22 leftward in FIG. 1 from the home position or the like, and executes forward printing based on the print data.

  Next, in step S206, the CPU 72 determines whether or not there is print data to be printed on the recording sheet S that is currently being printed. If there is print data, the process proceeds to step S208. The process proceeds to S218.

  Next, in step S208, a conveyance process for rotating the paper feed roller 35 and conveying the recording paper S by a predetermined amount is executed.

  Next, in step S210, ink is ejected from the print head 24 while the carriage 22 is moved rightward in FIG. 1 by driving the carriage motor 34, and backward printing is executed based on the print data.

  Next, in step S214, the CPU 72 determines whether there is print data to be printed on the recording sheet S that is currently being printed. If there is print data, the process proceeds to step S216. The process proceeds to S218.

  Next, in step S216, the paper feed roller 35 is rotationally driven to execute a transport process for transporting the recording paper S by a predetermined amount, and the process proceeds to step S202.

  In step S218, the CPU 72 executes a paper discharge process for discharging the recording paper S. The paper discharge process is a process of rotating the paper discharge roller 37 to discharge the recording paper S to the paper discharge tray. After step S218, this print processing routine is terminated.

  Returning to the description of the main routine of FIG. 5, in Step S124, it is determined whether or not Flag indicating whether cleaning is required after printing is ON. If Flag is ON, the process proceeds to Step S126 and cleaning is performed. If the flag is OFF, the main routine processing is terminated.

  According to the present embodiment described above, the following effects can be obtained.

  In this embodiment, if the color detected when there is a clogged nozzle is hardly used in the print data, the cleaning is performed after printing, so the waiting time until the completion of printing is shortened compared with the case where cleaning is performed before printing. In addition, by performing cleaning in the idle time after printing, it is possible to ensure the printing quality in the next print job.

  The embodiments of the ink jet printer have been described above. However, the present invention is not limited to these embodiments, and can be implemented in various forms without departing from the spirit of the invention. Hereinafter, a modification will be described.

  (Modification 1) Modification 1 of the ink jet printer will be described. In the first embodiment, the case of using one determination table shown in FIG. 6 has been described, but it may be defined for each print quality. Further, when monochrome printing is designated, determination may be made only with black (K), and with photo printing, determination may be made with yellow (Y), magenta (M), and cyan (C). Moreover, although it has been described that the determination is based on the number of ejections for each color, the determination may be made based on the ratio between the total number of ejections of all colors and each color.

1 is a perspective view illustrating a configuration of an inkjet printer according to a first embodiment. FIG. 3 is a block diagram illustrating a configuration of a print head. The block diagram which shows the structure of a paper feed mechanism. The block diagram which shows the structure of a nozzle test | inspection apparatus. The flowchart which shows operation | movement of an inkjet printer. The table figure which shows the structure of a determination table. 6 is a flowchart showing an operation of a print processing routine. The flowchart which shows operation | movement of a nozzle test | inspection routine. Explanatory drawing of the test | inspection position in a nozzle test process. Explanatory drawing of the principle which an induced voltage produces by electrostatic induction. Explanatory drawing which shows an example of threshold value Vthr.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 14 ... Paper feed tray, 18 ... Recording paper insertion port, 20 ... Inkjet printer, 21 ... Printer mechanism, 22 ... Carriage, 23, 23Y, 23M, 23C, 23K ... Nozzle, 24 ... Print head, 25 ... Linear encoder, 26 ... Ink cartridge, 28 ... Guide, 31 ... Paper feed mechanism, 32 ... Carriage belt, 33 ... Drive motor, 34 ... Carriage motor, 35 ... Paper feed roller, 36 ... Paper feed roller, 37 ... Paper discharge roller, 40 ... Cap device, 43, 43Y, 43M, 43C, 43K ... Nozzle array, 44 ... Platen, 47 ... Mask circuit, 48 ... Piezoelectric element, 50 ... Nozzle inspection device, 51 ... Inspection box, 52 ... Inspection region, 53 ... Voltage application Circuit 54 ... Voltage detection circuit 54a ... Integration circuit 54b ... Inverting amplifier circuit 54c ... A / D conversion circuit 55 ... Upper side Ink absorber 56 ... lower ink absorber, 57 ... electrode member, 70 ... controller, 72 ... CPU, 73 ... ROM, 74 ... RAM, 75 ... flash memory, 79 ... interface (I / F).

Claims (5)

An ink jet printer that performs printing on a print medium using a print head having a plurality of nozzles that discharge print recording liquids composed of a plurality of colors,
Driving means for driving the print head so that the printing recording liquid is discharged from the nozzle;
Detection means for driving the print head from above an inspection area provided at a position where the print medium is not disposed and outputting discharge information indicating whether or not the print recording liquid has been discharged from the nozzle of the print head;
Control means for executing the detection means for each nozzle in a state where the print head is disposed above the inspection area;
A non-discharge number calculating means for calculating the number of clogged nozzles that were not discharged for each color from the discharge information;
A discharge number calculating means for analyzing the image data to be printed and calculating the number of discharges for each color discharged for printing;
A cleaning determination means for determining whether or not to clean the print head based on the number of clogged nozzles and the number of ejection times when the total number of clogged nozzles is 1 or more;
including,
An inkjet printer characterized by the above.   2. The inkjet printer according to claim 1, wherein the inkjet printer includes a determination table defining the number of clogged nozzles and the number of ejections for each color for determining that the cleaning is performed, and the cleaning determination unit. Determines whether or not the print head is to be cleaned based on the determination table.   2. The ink jet printer according to claim 1, wherein the print head is cleaned after printing when the total number of clogged nozzles is 1 or more and the cleaning determination unit determines not to perform cleaning while waiting for printing. Inkjet printer characterized by. A nozzle cleaning method for an ink jet printer that performs printing on a print medium using a print head having a plurality of nozzles for discharging a printing recording liquid having a plurality of colors,
A driving step of driving the print head so that the printing recording liquid is discharged from the nozzle;
A detection step of driving the print head from above an inspection area provided at a position where the print medium is not disposed and outputting discharge information indicating whether or not the print recording liquid has been discharged from the nozzle of the print head;
A control step of executing the detection step for each of the nozzles in a state where the print head is disposed above the inspection region;
A non-discharge number calculating step of calculating the number of clogged nozzles that were not discharged for each color from the discharge information;
A discharge number calculating step of analyzing the image data to be printed and calculating the number of discharges for each color discharged for printing;
A cleaning determination step of determining whether to perform cleaning of the print head based on the number of clogged nozzles and the number of ejection times when the total number of clogged nozzles is 1 or more;
including,
A nozzle cleaning method for an inkjet printer. A nozzle cleaning control program for an ink jet printer that performs printing on a print medium using a print head having a plurality of nozzles for discharging a print recording liquid having a plurality of colors,
A driving step of driving the print head so that the printing recording liquid is discharged from the nozzle;
A detection step of driving the print head from above an inspection area provided at a position where the print medium is not disposed and outputting ejection information indicating whether or not the print recording liquid has been ejected from the nozzle of the print head;
A control step of executing the detection step for each of the nozzles in a state where the print head is disposed above the inspection region;
A non-discharge number calculating step of calculating the number of clogged nozzles that have not been discharged for each color from the discharge information;
An ejection number calculating step for analyzing the image data to be printed and calculating the number of ejections for each color ejected for printing;
A cleaning determination step of determining whether or not to clean the print head based on the number of clogged nozzles and the number of ejections when the total number of clogged nozzles is 1 or more;
including,
A nozzle cleaning control program for an ink jet printer.

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